Variable radio tuning device



Nov. 26, 192 9. c. SMITH VARIABLE RADIO TUNING DEVICE Filed Aug. 20, 1927 3 Sheets-Sheet Nov. 26, 1929. c. SMITH 1,737,063 v VARIABLE RADIO TUNING DEVICE Filed Aug. 20, 1927 3 Sheets-Sheet 2 ggi- Nov. 26, 1929. c. SMITH 1,737,063

VARIABLE RADIO TUNING DEVICE Filed Aug. 20, 1927 s Sheets-Sheet 5 Patented Nov. 26, 1929 UNITED STATES PATENT OFFICE CHARLES SMITH, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO WILLIAM CASEY, OF CHICAGO, ILLINOIS VARIABLE RADIO TUNING DEVICE Application filed August 20, 1927. Serial No. 214,295.

The device of the present invention is intended primarily for use in connection with single dial control radio sets in which it is desirable to simultaneously impart rotation t0 a series of condensers in which local conditions require that there should be slight individual variations from complete uni formity in collective rotation or adjustment, and the invention is so designed that by the turning of a single dial, each of the condensers or other tuning devices will be simultaneously rotated to the intended degree, each of the instrumentalities being concurrently compensated to a degree to be deter- 1 mined by individual adjustment.

Although in the drawings and description the device is shown in conjunction with the stator and rotor elements of a variable condenser, for which it is peculiarly fitted, nevertheless it will be understood that the device has application to other instrumentalities employed in radio tuning, such as inductances, resistances, or the like, which when operated in series from a single dial control requires 13 individual compensatory adjustment in order to secure a completely harmonized tuning of the instrument.

Further objects and details will appear from a description of the invention in conjunction with the accompanying drawings wherein Figure 1 is a sidelelevation of a condenser showing the cam housing located at one end of the condenser frame; 15 Fig. 2 is a plan View showing the housing and cam and a portion of the frame in section;

Fig. 3 is a sectional elevation through the frame showing the inner edge of the cam and cam housing;

Fig. 4 is a diagram showing a series of condensers coupled together in a manner required in the. present inyention,

Figure 5 is a plan view s1m1lar to Fig. 2 showing a modification of the arrangement;

Fig. 6 is a detail illustrating a face View of the cam of Fig: 5; and

Fig. 7 is a fragmental vertical elevation showing the cam and cam housing in section.

In the construction shown in Figs. 1, 2 and 59 3, the condenser is mounted within a frame local pecularities.

comprising a pair of rectangular end plates 10 and 11 of open formation, each of which end plates is provided on its upper edge with an enlarged or protruding portion 12 for the passage through the plate of a shaft 13. The shaft is j ournaled at each side through outer and inner bushings 14 and 15, respectively, and the intermediate portion of the shaft carries a sleeve 16, which in turn carries a plurality of thin condenser blades or plates 17 which, en banc, constitute the rotor series of the condenser, the sleeve 16 being held in fixed relation on the shaft 13 by the provision of a set screw 18, or the like.

The rotor plates 17 co-operate with a series of stator plates 19, the ends of which are mounted within brackets 20 carried by supporting bars 21-21 of insulating material, which supporting bars constitute the side members of a cradle which comprises end hangers 2222 of substantially triangular open work formation, as indicated in Fig. 3. Each hanger springs upwardly to a journal head 23 which is freely mounted upon the shaft 13, being mounted in each instance between the proximate inner bushing 15 and the adjacent end of thesleeve 16. The arrangement is one which permits the rotor plates to swing uniformly with the rotation of the shaft 13, and permits the stator plates so to remain stationary, save for the compensating adjustment now to be described, which adjustments are special to each of the condensers operated from the continuously engaging shaft 13. That is to say, in the series of condensers, all of the rotor plates will be moved to the same degree, while the stator plates will be individually moved to a slight extent in each condenser to compensate for The cradle which houses the stator plates is adjustable through the action of an obliquely disposed link 24 (Fig. 3), the lower end of which is pivoted on an outstanding pin 25 to the lower portion of one of the hangers 22, while the upper end of the link is carriedby a pin 26 which passes through a slot 27 in the upper portion of the proximate frame 11, so that a back and forth movement of the pin within the slot will result in a swinging movement of the cradle with the stator plates carried thereby. The pin 26 at its outer end carries a grooved roller 28 which bears against an arcuate cam track 29 formed of thin spring steel or the like, the configuration of which may be adjusted to present a departure from true circularity, so that as the roller 28 rides upon the cam track, it will be shifted back and forth to such slight extent as may be necessary to impart the re-.

quired compensatory movement to the stator plate series of the condenser.

The arcuate cam track is supported and adjustable by means of a somewhat closely spaced series of screw pins 30 which extend outwardly through the rim 31 of a plate housing 32, which is provided in its center with a hub 33, which is fixedly mounted upon the shaft 15 and held in position by a set screw 34 or otherwise. The pins 30 are surrounded by coil springs 35 which bear against the outer face of the cam track, and the screw pins are adjustable by the provision of thumb nuts 36 which bear against the outer wall of the housing rim. The arrangement is one which permits the configuration of the cam track to be adjusted within the necessary limits, and each of the condensers of the series operable from a single shaft control will have its cam plate properly adjusted and set to impart the necessary compensatory movements to the stator plates to secure harmonized tuning throughout.

A coil spring 37 is hooked onto the lower end of the link 24 and connected at its opposite end to the frame 11, and this spring serves to hold the roller 28 on the upper end of the link 24.

Figure 4 diagrammatically illustrates a series of three condensers all operable from the dial knob 38 on the shaft 13 and illustrates the method of securing absolute uniformity in the rotative movements of the three sets of rotor condenser plates in conjunction with variable compensatory movements of the stator plates in the slight degree required in each instance to secure harmonized tuning.

The construction of Figs. 5, 6 and 7 which is one of many possible modifications of the construction first described, differs in the main therefrom in that the series of rotor condenser plates co-operates with a series of absolutely fixed stator plates, which latter series is supplemented by a single stator plate hingedly mounted in such a way as to be moved by adjusted cam action to the degree required to afford the necessary compensation. The shaft with its mountings, the main frame and the rotor series of plates are identical with those heretofore described, so that special reference thereto is unnecessary.

The stator series of plates 19 are mounted in the brackets .20 carried by the insulated bars 21* identical with the parts heretofore described. In this instance, however, the bars 21 instead of constituting portions of a crathe frame 11, so that movement is impossible. The outermost plate 19* at one end of the stator series has located in adjacent relation thereto a supplemental swinging stator plate 39 of generally rectangular formation and of a length and width substantially equal to the series of stator plates with which it operates.

The supplemental stator plate near its lower corner is provided with laterally turned cars 40 which are pivoted upon pivot pins 41 carried by inwardly extending bracket arms 42 mounted upon the adjacent end plate 11 in the frame. This arrangement constitutes a hinge for the lower edge of the plate and allows the upper edge to swing freely toward and from the adjacent series of fixedly mounted stator plates.

Compensatory swinging motions areim parted to the supplemental stud or plate through the action of a thrust pin 43 which is slidably mounted within a bushing 44 located in the frame wall, and the thrust pin terminates at its outer end in a grooved head 45 which bears against the surface of an arcuate cam track 46 which is carried by the cam housing 32, similar to the housing previously described, which cam housing is fixedly mounted upon the shaft 13. In this instance, the surface of the cam track is adjusted to present a departure, in more or less degree, from a plane surface in which respect the configuration of the cam track 46 differs from the cam track 29 which is adjusted to present a departure from true circularity.

The adjustment of-the various portions of the cam track 46 is effected through the medium of screw pins 47 which are secured to the cam track and extend outwardly through the face of the cam housing and carry thumb nuts 48/ for purposes of adjustment. Springs 49 are lnterposed to bear against the rear face of the cam track to maintain the same in proper position. The coil spring 50 encircles one of the pins 41, and has one of its ends held in fixed relation to the adjacent bracket 42 and its other end in fixed relation to the supplemental stator plate 49, the tension spring being such as to exert a backward pull sufiicient to hold the plate firmly against the end of thethrust pin 43.

The operation of the two modifications is quite similar, but reference will first be made to the form shown in Figs. 1, 2 and 3. A rotation of the shaft 13 will rotate in unison the several sets of rotor plates mounted upon the shaft, and the rotation of the shaft will in each instance cause a rotation of the cam housing and cam carried thereby. If the cam be adjusted to present a truly circular configuration, no movement will be imparted to the roller 28 carried by the link'24.

If, however, the cam track be adjusted to present a departure from true circularity, the contact of the roller 28 against the cam track, which turns past the roller, will cause a shifting of the roller with a socket pull or thrust upon the link 24 which will swing the cradle which carries the set of stator plates,;

and the degree of this swinging movement? and the timing thereof, can be accurately provided for by adjusting the various screw pins which support the camtrack, so that the proper configuration can be given to impart the necessary compensatory movements in the degree, and, at the same time, required to secure harmonious tuning from a single dial control.

In the construction of Figs. 5, 6 and 7 the turning of the shaft with the rotor sets will impart a like degree of movement to the several cam tracks which are individually adjusted to impart the necessary compensatory movements to the supplemental stator plate which is hingedly mounted to permit its free edge to swing toward and from fixed stator plates, so that such independent compensatory movements will in each instance compensate for lack in complete uniformity in the several condensers due to local conditions.-

'In so far as the application of the principles of the present invention is concerned, it is immaterial whether the entire series of stator plates be subjected to the supplemental movements, or whether such movements be combined to but one of the stator series, since, in each case, the compensating result will be realized through the medium of a cam track and connections operable by the turning movement of the shaft which controls the entire series.

It is not the intention, unless otherwise indicated, to limit the invention strictly to an arrangement in which the rotor elements are mounted upon a shaft, or to any particular 'relation of adjustment between the stator and rotor elements, since other methods of securing relative adjustment between the condenser plates may readily be em ployed. \Vith suitable modifications in detail, the present invention may be adapted I to any construction in which sets of uniformly niovable plates are employed in conjunction with companion sets which are moved in whole or in part through compensating connections which derive their movements, in individuallyadj usted degree, from the movements imparted to the uniformly. movable sets of plates.

Furthermore, although the present invention has been described with reference to its use in connection with the plates of a condenser, it is obvious that the principles involved are applicable to other series of instrumentalities in a radio receiving set or the like, and in which a harmonized tuning or similar adjustment is desirable for each instrumentality in the singly controlled set.

I claim:

1. In mechanism of the class described consisting of a plurality of instrumentalities in co-operative relation and. adapted to be adjusted from a single point of control, a main movable controlling element adapted to impart movement in equal degree to each of said instrumentalities, members comprised in each of said instrumentalities and connected with said main controlling element and adapted to be moved in equal degree by movements imparted therefrom, complementary elements co-operating with said movable elements and connections therefor, said connections comprising in each instance an individually adjustable cam track and a member cooperating therewith and adapted to impart independent compensatory movements to the complementary elements in an amount variably determined by the configuration of the cam track, substantially as described.

2. In mechanism of the class described consisting of a plurality of instrumentalities in cooperative relation and adapted to be adjusted from a single point of control, a main rotatable controlling element adapted to impart movement in equal degree to each of said instrumentalities, rotatable members comprised in each of said instrumentalities and connected with said main controlling element and adapted to be rotated in equal degree by movement imparted therefrom, complementary elements co-operating with said rotatable elements and connections therefor, said connections comprising in each instance an individually adjustable cam track and a member co-operating therewith and adapted to-impart independent compensatory movements to the complementary elements in an amount variably determined by the configurationof the cam track, substantially as described.

3. In mechanism of the class described consisting of a plurality of instrumentalities in co-operative relation and adapted to be adjusted from a. single point of control, a main rotatable controlling element adapted to impart movement in equal degree to each of said instrumentalities, rotatable members comprised in each of said instrumentalities and connected with said main controlling element and adapted to be rotated in equal degree by movement imparted therefrom, complementary elements co-operating with said rotatable elements and connections therefor, said connections comprising in each instance an individually adjustable cam track and a member co-operating therewith and adapted to impart independent compensatory movements to the complementary elements in an amount variably determined by the configuration of the cam track, said cams being rotated with the main rotatable controlling element, substantially as dBSCI'lbGCL 4. In mechanism of the class described consisting of a plurality of instrumentalities adapted to be adjusted in unison from a smgle point of control, a main rotatable shaft common to all of said instrumentalities, rotor elements in each of said instrumentalities connected with said shaft and adapted each to be moved to the same degree by the rotation of the shaft, a complementary element in each of said instrumentalities, a cam track for each of said instrumentalities, each cam track being rotatable to an equal degree by rotation of the shaft, and individually adjustable connections between the respective cam tracks and the associated complementary elements for imparting to the latter independent compensatory movements in a degree commensurate with the configuration of the associated cam track, substantially as described.

5. In mechanism of the class described consisting of a plurality of instrumentalities adapted to be adjusted in unison from a single point of control, a. main rotatable shaft comnoon to all of said instrumcntalities, rotor elements in each of said instrumentalities connected with said shaft and adapted each to be moved to the same degree by the rotation of the shaft, a complementary element in each of said instrumentalities, a cam track for each of said instrumentalities, each cam track being rotatable to an equal degree by rotation of the shaft, individually adjustable connections between the respective cam tracks and the associated complementary elements for imparting to the latter independent compensatory movements in a degree commensurate with the configuration of the associated cam track, and means for each of the cam tracks for adjusting the configuration thereof, substantially as described.

6. In a device of the class described consisting of a plurality of instrumentalities adapted to be simultaneously adjusted from a single point of control, a main controlling shaft common to all of said'instrumentalities, a rotor element in each of said instrumentalities carried by the shaft, a complementary stator element in each of said instrumentalities in co-acting relation to the rotor element, and compensating connections between each of said stator elements and the shaft, said connections being individually adjusted to impart independent compensatory movements to the associated stator element, said connections in each instance including a cam track for regulating the movements imparted, and means for individually adjusting the configuration of each cam track, substantially as described.

CHARLES Sit HT 

